Assessment of Design Procedures for Vertical Borehole Heat Exchangers

The use of ground source energy systems is a well-established method to provide low cost heating to buildings, diversify the energy mix and help meeting increasingly stricter sustainability targets. However, considerable uncertainties remain over their efficient design, with several standards, guidelines and manuals being proposed over the last few years. This paper aims at providing insight into the implications to the design of a vertical borehole heat exchanger of the adoption of different design procedures. The hypothetical case of a typical dwelling located in London, UK, is analysed in order to highlight the impact on the final design of the chosen methodology. Moreover, a parametric study using an analytical design procedure was performed to point out the influence of various factors, such as borehole characteristics and thermal properties of the ground. It is shown that there are considerable discrepancies between design methods and that uncertainties in some input parameters, such as the thermal properties of the ground, which for relatively small systems are often selected from tables rather than measured in situ, may have a substantial influence on the length of borehole required

Catheter-associated urinary tract infection in medical patients of a Portuguese hospital: incidence and risk factors

info:eu-repo/semantics/publishedVersio

Early Portuguese meteorological measurements (18th century)

Natural proxies, documentary evidence and instrumental data are the only sources used to reconstruct past climates. In this paper, we present the 18th century meteorologists (either Portuguese or foreigners) who made the first observations at several sites in Continental Portugal, Madeira Island and Rio de Janeiro (Brazil), from 1749 until 1802. Information is given concerning observation site, variables observed, measurement period, methods of measurements and sources (both manuscript and printed). Some examples from the data usefulness are given: rainfall variability in Madeira (1749–1753) and in continental Portugal (1781–1793) was reconstructed, allowing to extend towards the late 18th century the well known negative correlation between the NAO index and seasonal rainfall. Furthermore, previously unpublished data for 1783–1784 have allowed analysing the consequences of the Lakagígar eruption in Portugal: foggy and haze days are referred to in summer 1783, but unlike the hot summer observed in northern and central Europe, temperatures in Portugal were lower than average. Additionally, observations from Rio de Janeiro in Brazil show that the Lakagígar consequences may well have spread to sectors of the Southern Hemisphere. Although the series are short, the data have been used for climate reconstruction studies and may also be useful to improve the quality of large scale reconstruction datasets.info:eu-repo/semantics/publishedVersio

Measurements of suspended sediment transport on a reflective mesotidal beach in southern Portugal

The present paper reports the results obtained in a field experiment carried out on a medium- energy, mesotidal, reflective beach on Culatra Island (southern Portugal). Simultaneous time-series measurements of waves, currents and sediment concentration were taken during 1.5 tidal cycles using a pressure transducer, two bidirectional electromagnetic current-meters and three optical backscatter sensors. Measurements of suspended sediment transport were compared with fluorescent sand tracers. Total longshore sediment fluxes measured with optical techniques and sand tracers were found to give similar results, if their major limitations are considered. The present experiment confirms the different sedimentary behaviours of steep reflective beaches with plunging breakers, as opposed to the low-gradient beaches with spilling breakers where most previous studies have been performed, and supports the idea that one of the major limitations of longshore sediment transport models is their lack of dependency on breaker/beach type.Se presentan los resultados de un experimento realizado en una playa reflectiva, mesotidal y de media energía, en la isla de Culatra (sur de Portugal). Se llevaron a cabo mediciones de series temporales de olas, de corrientes y de concentración de sedimento en suspensión durante un ciclo tidal y medio, utilizando un transductor de presión, dos correntímetros bidireccionales electromagnéticos y tres sensores ópticos. Se constató que los resultados de medir los flujos sedimentarios con las técnicas ópticas y con arenas marcadas eran semejantes, teniendo en cuenta las respectivas limitaciones. El presente experimento ha confirmado el desigual comportamiento sedimentario de playas reflectivas con fuerte inclinación y rompiente en voluta, en oposición a las playas con pequeña inclinación y rompiente en derrame, apoyando, pues, la idea de que una de las mayores limitaciones de los modelos de deriva litoral es la ausencia de dependencia en relación al tipo de playa/ rompiente.Instituto Español de Oceanografí

La brotación y la floración del kiwi en función de las temperaturas invierno - primaverales de la región central de Córdoba

p.183-188Se analizaron la brotación y floración del kiwi en relación a la acumulación de unidades Richardson en dos localidades de la región central de Córdoba durante las campañas agrícolas 1990-91 y 1991-92. Se observaron diferencias significativas entre los cultivares Hayward y M- 54 en cuanto a las fechas de ocurrencia de la brotación. El porcentaje de yemas brotadas estuvo relacionado con el nivel del enfriamiento invernal. Asimismo, la duración de la floración, en particular de las flores femeninas, se reduce al producirse una mayor acumulación de unidades de Richardson. Las condiciones meteorológicas registradas en las localidades estudiadas durante el período de la dormición invernal fueron propicias para el posterior desarrollo de la brotación y floración del kiwi

Prevalence of asthma and allergies in 13–14-year-old adolescents from Luanda, Angola

SETTING: The few epidemiological studies on asthma and allergic diseases performed in Africa have shown that the prevalence of these diseases is high or increasing. No such studies have been performed in Angola. OBJECTIVE : To determine the prevalence of asthma and other allergic diseases in Angolan adolescents. DESIGN: This was a descriptive, observational, crosssectional study in the province of Luanda, Angola, using the International Study of Asthma and Allergies in Childhood study methodology in adolescents aged 13 and 14 years. Twenty-three (12%) public schools were randomly selected. Data were analysed using the Statistical Package for the Social Sciences version 22.0 software. RESULTS : A total of 3128 adolescents were included. The prevalence of asthma (wheezing in the previous 12 months) was 13.4%. The prevalence of rhinitis (sneezing, runny or blocked nose in the previous 12 months) was 27% and that of eczema (itchy skin lesions in the previous 12 months) was 20%; both were more prevalent in girls. Rhinitis was associated with a greater number of episodes of night cough in adolescents with asthma. Rhinitis and eczema, a split-type air conditioning system, and frequent intake (more than once per month) of paracetamol were associated with a higher risk of having asthma. CONCLUSION: Asthma and related allergic diseases are a public health problem in adolescents from Luanda. Preventive and control measures should be implemented.info:eu-repo/semantics/publishedVersio

Impacto da pandemia da COVID-19 nas associações de cultura, recreio e desporto: Os casos de Portugal e Brasil

As nações portuguesa e brasileira compartilham, historicamente, importantes simetrias. Estes enlaces históricos são salutares para compreendermos semelhanças que ainda se reproduzem em tempos atuais, como é o caso do contexto associativo. Em casos de países como Brasil e Portugal, o período de transição democrática (marcado pela instituição das Constituições de 1976 em Portugal e 1988 no Brasil) estabeleceu-se enquanto período de grande florescimento de movimentos da sociedade civil, principalmente daquelas associações que já possuíam maior enraizamento no tecido social. No caso das associações de cultura, recreio e desporto, os dados dos institutos nacionais de pesquisa demonstram que estas constituem, nos dois países, um tipo associativo muito expressivo (em número de unidades), sendo ao mesmo tempo dos mais antigos e com maior longevidade.info:eu-repo/semantics/publishedVersio

INCORPORACIÓN DE SISTEMAS MULTI-AGENTES EN EL APRENDIZAJE DE LA CULTURA E HISTORIA DE SANTA MARTA, COLOMBIA

Este artículo plantea una forma de aprendizaje de la cultura e historia de Santa Marta, haciendo uso de técnicas de Inteligencia Artificial para crear un STI (Sistema Tutorial Inteligente) en el tema, que pueda adaptarse a los diferentes perfiles de usuarios y estilos de aprendizaje. Se muestra una aproximación metodológica y la estructura organizacional planteada para el modelo del usuario, teniendo en cuenta que ésta es la primera forma de adaptación del sistema. Los Sistemas Multi-Agentes es la técnica de Inteligencia Artificial que brinda la posibilidad de adaptación a los perfiles de usuario (estudiantes y turistas) además de los estilos de aprendizaje. Se pretende otorgar gran importancia al rol del turista el cual es muy importante en la ciudad de Santa Marta (distrito turístico, cultural e histórico), brindándole la posibilidad de aprender sobre la ciudad y ejercer turismo cultura en la misma, generando así una interacción dinámica entre el sistema y los usuarios (estudiantes y turistas), facilitando el proceso de aprendizaje por parte de los alumnos, así como la exploración cultural por parte de los turistas en la ciudad de Santa Marta

Energy supply optimization for unregulated consumers

El presente artículo propone un modelo de optimización del portafolio de abastecimiento de energía eléctrica para consumidores finales no regulados en el mercado de electricidad colombiano. El propósito del modelo es determinar la cantidad óptima de energía que debe ser suministrada por cada una de las tres formas de abastecimiento disponibles para el usuario: compra basada en mercado spot, compra mediante contratos bilaterales y cogeneración, minimizando el costo esperado de abastecimiento de energía y el valor en riesgo asociado. Para este objetivo se usa un modelo de optimización estocástica y el indicador de riesgo empleado es el valor en riesgo condicional ( Conditional Value at Risk-CVaR). Finalmente, se estudian los resultados del modelo a través de escenarios de precios simulados basados en los precios reportados en el sistema de información NEON administrado por XM S.A., operador del mercado de electricidad colombiano y se selecciona el mejor ejemplo de aversión al riesgo. Abstract A supply electricity portfolio optimization model for unregulated consumers in the Colombian electricity market is proposed in this paper. The purpose is to choose between three supply alternatives available to the consumers: spot market purchase, purchase by bilateral contracts and self-generation, minimizing the total expected cost and the risk associated to these decisions. For this objective, a stochastic optimization model is used and the risk indicator is the conditional value at risk (CVaR). Finally, the model results are analyzed through the application of simulated prices based on real price observations from the database managed by XM – the Colombian Market Operator, and the best instance of risk aversion is selected

Hypercalcemic crisis associated with primary hyperparathyroidism during pregnancy

Primary hyperparathyroidism is a rare occurrence in pregnancy with significant risks to the mother and the foetus, witch is related to the level of serum calcium. A 41-year-old women, gravida 2, para 1, presented at 22 weeks gestation with nausea, vomiting and mild cognitive dysfunction associated with hypercalcemic crisis. The hypercalcemia was observed to be related to parathyroid hyperplasia that was surgically removed. Complete resolution of her symptomatology and hypercalcemia occurred postoperatively. The pregnancy was complicated with transient hypertension. A small for gestational age healthy male infant was delivered at term with no neonatal complications related with this pathology